JPH048106B2 - - Google Patents

Abstract

The dispersions, supersaturated in OH<-> ions, are prepared directly from the aqueous solution of the cerium(IV) salt by reacting the said solution with a base so as to obtain a degree of supersaturation higher than 3 and lower than 4.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a novel aqueous colloidal dispersion of cerium () compounds supersaturated with OH ^- ions and a process for their preparation.

[Prior art and its problems]

“Encyclopedia” edited by Kirk Othmer
of Chemical Technology (Eneyelopedia)
of Chemical Technology) 2nd edition, p. 850, cerium dioxide hydrate, which corresponds to the formula CeO ₂ xH ₂ O (where x is 0.5 to 2) and exhibits a gelatinous precipitate, is It is known that it can be produced by adding sodium hydroxide or ammonium to a cerium salt solution.

Also, according to French Patent No. 2416867,
Form a suspension of cerium hydroxide () with water and an acid capable of inducing dissociation of microcrystals, and maintain this suspension for a period and at a temperature such that its pH remains at a stable value. The treatment is heated to form a suspension and the amount of acid present in the suspension is controlled by this stable
A method for producing an aqueous dispersion of cerium oxide is proposed, which comprises preparing an aqueous dispersion of cerium oxide such that the pH value is 5.4 or less, and mixing water with the resulting suspension to form an aqueous dispersion of cerium oxide. .

This patent also states that the production of cerium oxide () hydrate can be carried out by precipitation from cerium salts. However,
For example, high-purity cerous carbonate is dissolved in nitric acid or hydrochloric acid solution to form a neutral solution of nitric acid or cerous chloride, and this is oxidized with NH ₄ OH/H ₂ O ₂ to form cerium oxide () water. You can get a Japanese version.

Herein, starting from an aqueous solution of cerium() salt, the inventors have determined that, in the course of the process, cerium() in an aqueous medium without intervening precipitation and separation steps of ceric hydroxide and subsequent treatment. A novel colloidal dispersion of the compound was obtained.

[Specific description of the invention]

One of the objects of the present invention consists of novel aqueous colloidal dispersions of cerium () compounds supersaturated with OH ^- ions.

By the way, the solubility product of ceric hydroxide is
Knowing that 10 ^-56 is equal to 10 -56, we can define the pH range in which ceric hydroxide is stable as a solid precipitate as a function of concentration.

The inventor has now found that it is possible to obtain cerium () in the form of a colloidal dispersion in the PH zone where it was naturally expected to obtain it in the form of a precipitate of ceric hydroxide.

An advantage of the invention is that the aqueous colloidal dispersions of cerium() compounds according to the invention have very high colloidal cerium contents which can reach up to 100%.

Also, an advantage of the present invention is that the colloidal dispersion is stable at ambient temperature and when subjected to temperature increases up to 100°C.

Additionally, another advantage of the present invention is that the colloidal dispersion has less acidic properties (PH of about 3 or less).
It is to show that.

The dispersion with the above characteristics is cerium ()
It was obtained by a method consisting of reacting an aqueous solution of the salt with a base so as to obtain a supersaturation ratio of 3 or more and 4 or less.

First, before defining this supersaturation rate, the types of reactants used in the method of the present invention will be explained in detail.

The solution of cerium salt used by the method of the invention may be an aqueous ceric nitrate solution or an aqueous cerium ammonium nitrate solution. Such solutions can contain cerium in the cerous state without any problems, but preferably contain at least 85% cerium ().

The cerium salt solution is selected so that it does not contain impurities that may be found in the final product. In particular, it is preferred that the cerium salt solution does not contain aggregating covalently bonded anions such as sulfuric acid. However, the presence of trace amounts is acceptable. For example, such anions may be present in amounts up to 5% by weight of the cerium salt (expressed as _CeO2 ).

According to the invention, the concentration of the cerium salt solution is not a critical factor. This concentration, expressed in cerium (), may be from 0.1 to 3 mol/mole. 0.1
A concentration of ~1.5 mol/mole is preferred.

Aqueous solutions of cerium () salts generally exhibit some initial acidity and may have a normality of 0.1N to 4N. However, the H ⁺ ion concentration is not critical.
This concentration is preferably between 0.1N and 1N.

The ceric nitrate solution obtained by the electrolytic oxidation process of cerous nitrate solution and described in French Patent No. 2,570,087 constitutes a particularly selected raw material.

The basic solution used by the method of the invention may be, in particular, an aqueous solution of ammonia, caustic soda or caustic potash. Gaseous ammonia can also be used. According to the invention, preferably an ammonia solution is used.

The normality of the basic solution used is not a critical factor in the present invention, and can vary within a wide range, for example from 0.1N to
May be between 11N, but CE()
In order to obtain a solution with a concentration of
Preferably, a 5N solution is used.

The ratio of basic solution to cerium () salt solution must be such that the supersaturation rate is 3 or more and 4 or less.

The supersaturation rate r is defined by the following equation.

r=n3−n2/n1 where n1 is Ce present in the final colloidal dispersion
(), n2 represents the number of moles of OH ^- required to neutralize the acidity provided by the aqueous solution of cerium () salt, and n3 represents the number of moles of OH ^- provided by the addition of the base. Represents the total number of moles.

This supersaturation rate reflects the colloidal state of cerium (). That is, when r=4, cerium () is precipitated in gelatinous form, when r=0, cerium () is ionic, and when 0<r<4.0, cerium () is ionic and/or colloidal.

The inventors have found that obtaining a colloidal dispersion of cerium() compounds from the two reactants mentioned above is linked to two parameters: the supersaturation rate of the dispersion and the final cerium() concentration. .

According to the invention, for the resulting colloidal dispersion between 0.1 M (i.e. 17 g/CeO2) and ₂ M (i.e. 344
A supersaturation ratio of 3 or more and 3.8 or less is chosen for the final cerium () concentration in g/CeO ₂ ). More preferably, this supersaturation rate is 0.5M
(i.e. 86g/CeO ₂ ) ~ 1.2M (i.e. 206g/
3.4 for the final cerium () concentration of CeO ₂ )
or more and 3.8 or less.

In practice, in order to obtain the desired supersaturation ratio r chosen in the range mentioned above for a given cerium() concentration in the final colloidal dispersion, the concentration of the basic solution must be such that it satisfies the following equation: adjusted to.

[OH ^- ] = (n ₁ .r + n ₂ ) [Ce (
)] _f [Ce()] _i / n ₁ ([Ce()] _i − [Ce()
〕 _f ) Here, 〔OH ^- 〕 represents the concentration of the basic solution (mol/), 〔Ce()〕 _q represents the Ce() concentration (mol/) of the final colloidal dispersion, and 〔Ce() ] _i represents the cerium() concentration (mol/) of an aqueous solution of cerium() salt, n ₁ and n ₂ are determined by the typical method of determination of an aqueous solution of cerium() salt, i.e., n ₁ is ferrous By potentiometric titration with a salt solution, n ₂ is determined by acid-base titration after axification of cerium with oxalate ions.

Therefore, for a given supersaturation rate, the amount of base introduced (the theoretical amount of base necessary to completely neutralize the cerium () present in the reaction medium to obtain Ce(OH) ₄ (expressed in mol %) can be made to correspond.

Thus, for a supersaturation ratio of 3 or more and 4 or less, a molar amount of the introduced base is 75% or more and 100% or less of the theoretical amount.

For example, for a supersaturation rate of 3.5 and 3.8, corresponding molar amounts of introduced base represent 87.5 and 95% of the theoretical amount, respectively.

One of the preferred embodiments of the invention consists in obtaining the supersaturation rate by controlling the PH of the reaction medium.

Obtaining a supersaturation rate of 4 or less corresponds to making the final pH of the colloidal dispersion of the cerium () compound 3.0 or less. For a supersaturation rate of 3 or more and 4 or less, the PH is 0.3 to 3.0.

Without limiting the scope of the present invention, as one specific example, the final
In the case of a ceric nitrate solution with a concentration such that the concentration of Ce() is 0.7M, the following
It becomes clear that the following supersaturation rates corresponding to the PH ranges can be obtained.

0.2<PH<0.7 3<r<3.3 0.7<PH<2.7 3.3<r<3.7 The reaction between the aqueous solution of cerium () salt used in the amounts specified above and the base is carried out between 0°C and 60°C. temperature, preferably at ambient temperature (often 15-25°C).

Mixing of the reactants described above can be accomplished in a variety of ways. For example, the aqueous solution of cerium () salt and the basic solution can be mixed simultaneously under stirring, or the base can be added continuously or all at once into the aqueous solution of cerium () salt, and vice versa.

According to a further preferred embodiment, a concentrated basic solution is added until a supersaturation ratio of 3.3, corresponding to a PH of 0.6 is obtained, and then the desired final PH is brought up with a thinner basic solution.

Mixing time is not critical and depends on the capacity of the equipment. This may be from 0.1 seconds to 30 hours.

Regardless of the order of introduction of the reactants, a colloidal dispersion of cerium() compounds in an aqueous medium is obtained. Hereafter, this will be referred to as "Sol".

According to the present invention, the cerium() compound exhibits the form of a colloidal dispersion in water, which means that the compound has particles of colloidal size, but this does not mean that the ionic Ce()
This does not exclude the existence of In addition, what can be said is that the proportion (%) of colloidal Ce() can be somewhat related to the supersaturation rate. r is 3.4 to 3.8
When , almost the entire cerium () is colloidal.

The chemical composition of the colloid was determined by determination of cerium () according to the method described above on the residue obtained after ultracentrifugation of the dispersion and by acid-base titration of NH ₄ ⁺ ions obtained after reduction of nitrate ions. Measured by quantitative determination of nitrate ions.

This composition corresponds to the following chemical formula () Ce(OH) _4-x (NO ₃ ) _x () (where x is 0.3 to 0.7). However, the presence of ammonium ions adsorbed on the colloidal particles can also be confirmed.

Analysis of the solid residue by X-ray diffraction shows that it is poorly crystallized exhibiting a fluorite-type, i.e., face-centered cubic CeO ₂ crystal phase with a lattice constant of about 5.42〓 and a crystallinity of 15-40%. Indicates complete product.

The aqueous sols obtained according to the invention can contain up to about 30% by weight of CeO ₂ and thus exhibit high cerium () compound concentrations.

Also, this aqueous sol can exhibit large ionic forces due to the presence of a high base salt concentration, which is between 0.3 and 0.8 mol/mol.

The density of a colloid is determined by determining the molecular weight of a colloidal dispersion by the classical diffusion of light method and by correlating it with the hydrodynamic diameter defined by the pseudoelastic diffusion of light method.

The density of the colloid is always smaller than that of CeO ₂ (d=7.2). The density is between 3.5 and 6.0 and increases with increasing supersaturation.

The size of colloids is explained by Michael L. McConnell in Analytical Chemistry Vol.53, No.
8, 1007A (1981) by measuring the hydrodynamic diameter of the colloid as measured by pseudoelastic diffusion of light.

The size of the colloid depends on the cerium () concentration and the supersaturation rate. For cerium() concentrations of 0.1 M to 2 M and supersaturation ratios of 3 to 3.8, the hydrodynamic diameter of the colloids is 50 to 400 Å.

It has been found that the sols obtained by the method of the invention are completely stable under normal storage conditions. This point will be demonstrated in Examples.

Another object of the present invention is to combine cerium () compounds with other metal cations M ⁿ⁺ (where n+ indicates the degree of oxidation of the metal, generally equal to +3 or +4).
in a mixed aqueous colloidal dispersion.

Metal cations (which are generally designated as metal M cations) are listed in the Handbook of
Groups 1b, 2b, and 3b of the periodic table as listed in Chemistry and phyaics B-4 (57th edition),
Cations of metals selected from Groups 4b, 5b, 6b, 7b, 8, 3a and 4a can be used.

Preferably metal cations with acidic properties are chosen.

By metal cations having acidic properties are meant cations whose metal hydroxides precipitate at low PH values, preferably below 4. Particularly preferred acidic cations include iron, titanium,
Mention may be made of the metal cations of zirconium and tin.

0.1 to 50% of the moles of cerium () can be replaced with the metal cations mentioned above.

The method for producing a mixed aqueous colloidal dispersion of a cerium () compound and a metal cation M ⁿ⁺ is similar to the method for producing a colloidal dispersion of only a cerium () compound.

Thus, according to the present invention, an aqueous solution of a cerium () salt and a salt of metal M is reacted with a base so as to obtain a supersaturation ratio of 3 or more and 5.5 or less, expressed with respect to cerium ().

The amount of base added is the theoretical amount of base in moles necessary to completely neutralize the cerium() and cations Mn ⁺ present in the reaction medium to obtain Ce(OH) ₄ and M(OH) _o . Expressed in %, it may be between 60 and 95%.

Practically speaking, if the supersaturation rate mentioned above is obtained, this becomes
Corresponds to a final PH of a hybrid aqueous colloid dispersion of 3.0 or less.

The characteristics of the reactants and the conditions for their use also correspond to those described above.

The metal M is preferably used in the same form as the cerium salt is present. These are preferably selected in the form of nitrates.

The salts of metal M can be used in anhydrous or hydrated form.

The salt of the metal M can also be used in solid form or in the form of an aqueous solution whose concentration is between 0.01 mol/mole and the maximum solubility of the metal salt used.

One embodiment of the invention consists in introducing the salt of metal M in solid form into the cerium () salt solution and then adding the base.

It is also possible to form the salt of the metal M into an aqueous solution, then mix this solution with an aqueous solution of the cerium () salt, and then carry out the addition of the base.

In this way a colloidal dispersion of cerium() compound and metal cation M ⁿ⁺ in an aqueous medium is obtained. This contains up to 30% by weight of _CeO2 and
Since it can contain M ₂ O _o , it exhibits a high concentration of cerium () compounds and metal M.

The hydrodynamic diameter of this colloid, determined by the method described above, is between 50 and 2000 Å.

〔Example〕

Various examples are presented below to further illustrate the practice of the invention. These do not limit the present invention in any way.

The first example illustrates the production of a colloidal dispersion by supersaturating a ceric nitrate solution with OH ^- ions.

Example 1 In a 6 three-necked flask equipped with a thermometer, a stirrer, and a reactant introduction system (metering pump), a sample containing 1.2 mol/cerium (), 0.04 mol/cerium () and 0.5N free acid Ceric nitrate (French patent no.
2570087) is introduced at ambient temperature.

First 6.6N at ambient temperature was added to this solution, which was kept stirring.
of concentrated ammonia solution is added gradually over 13.7 hours at a rate of 100 c.c./hour.

This was followed by OH ⁻ with 2.4N ammonia solution
Ions are added at a rate of 100 c.c./hour for 5 hours.

An aqueous colloidal dispersion of cerium () compound was obtained with a concentration of 107 g/C expressed in CeO ₂ and a pH equal to 2.67.

The percentage of colloidal cerium is determined by quantifying the total cerium in the supernatant solution obtained after ultracentrifugation (45000 rpm, 1 hour) by potentiometric titration with an iron titration solution. Quantification of cerium in the supernatant solution shows a very low total cerium concentration of around 0.02 molar, from which the amount of colloidal cerium in the supersaturated dispersion can be determined to be approximately 100%.

The size of colloids is explained by Michael L. McConnell in Analytical Chemistry Vol.53, No.
8, 1007A (1981).

The sol obtained in this example was found to exhibit good storage stability but no decantation even after storage for at least one year.

In the following example, a hybrid colloidal dispersion is prepared by supersaturating an aqueous solution of ceric nitrate and ferric nitrate.

Example 2 In an apparatus similar to that described in Example 1, 1.2 mol/
of cerium(), containing 0.04 mol/cerium() and having a free acidity of 0.5N
1744 c.c. of ceric nitrate solution and 86.15 g of ferric nitrate Fe( _NO3 ) _3.9H2O with _a purity of 98% are introduced.

This mixture, kept stirring, was heated to 1256 c.c. at ambient temperature.
Add 6.19N concentrated ammonia solution at a rate of 100 c.c./hour, followed by 100 c.c. of 2.48N ammonia solution.

An aqueous colloidal dispersion was obtained exhibiting a CeO ₂ concentration of the order of 116.13 g/g and a pH of 1.5.

Testing of the sample (290 c.c.) by pseudoelastic diffusion of light showed the presence of two colloidal populations with hydrodynamic diameters of 76 Å and 199 Å, respectively.

A subsequent addition of 2.48N ammonia solution for 66 minutes results in a CeO ₂ concentration of 111.7 g/ and equal to 2
An aqueous colloidal dispersion exhibiting a pH was obtained.

For the 240 c.c. sample, two colloidal populations were characterized by hydrodynamic diameters of 167 Å and 977 Å, respectively.

Addition of ammonia solution at a rate of 100c.c./hour
Continuing for 18 min, it shows two colloidal populations with hydrodynamic diameters of 229 Å and 1270 Å, respectively.
A dispersion with PH=2.56 was obtained.

The amount of base added in this way in the reaction medium corresponds to 84 mol% of the theoretical amount required to completely neutralize the cerium and iron present in the reaction medium (OH ^- /Fe ³⁺ = 3, OH ^- /Ce ⁴⁺ = 4).

The chemical composition of the substances present in colloidal form in the aqueous sol is then determined by drying the solid residue obtained by ultracentrifugation (45000 rpm, 1 hour) and at 1000 °C for 2 hours. It is measured by X-ray spectrophotometry after baking.

The Fe/Ce molar ratio determined by comparison with a standard sample with a clear Fe/Ce composition was approximately 0.1.

The following example illustrates the production of a mixed colloidal dispersion by supersaturating a mixed solution of ceric nitrate and zirconyl nitrate with OH ^- ions.

Example 3 55.85 in a 1744 c.c. ceric nitrate solution containing 1.2 mol/cerium (), 0.04 mol/cerium () and a free acidity of 0.5 N
g _{of zirconyl nitrate ZrO(NO3)2.2H2O are added} .

This mixture, kept stirring, was heated to 1256 c.c. at ambient temperature.
Add 6.19N ammonia solution at a rate of 100 c.c./hour, then add 165 c.c. of 2.48N ammonia solution at the same flow rate.

An aqueous colloidal dispersion was obtained with a CeO ₂ concentration of the order of 113.7 g/m and a PH of approximately 1.57.

The hydrodynamic diameter of the colloid was 121 Å when tested by pseudoelastic diffusion of light on a sample (250 c.c.).
It was determined that the extent of

Further, add 40 c.c. of 2.48N ammonia solution.

The amount of base thus added in the reaction medium is equal to the theoretical amount necessary to completely neutralize the cerium and zirconium present in the reaction medium.
Corresponds to 80 mol% (OH ^- /Zr ⁴⁺ = 4, OH ^- /
Ce4 ⁺ = 4).

An aqueous colloidal dispersion was obtained with a CeO ₂ concentration of the order of 112 g/d and a pH of 2.58.

The hydrodynamic diameter of the colloid, measured by light diffusion, is 490 Å.

The chemical composition of the substances present in colloidal form in the aqueous sol was determined as described above.

The determined Zr/Ce molar ratio was approximately 0.1.

Example 4 320.7 in a 1000 c.c. ceric nitrate solution containing 1.2 mol/cerium (), 0.04 mol/cerium () and having a free acidity of 0.5 N
g of zirconyl nitrate ZrO(NO ₃ ) ₂ ·2N ₂ O is added. The Zr ⁴⁺ /Ce ⁴⁺ molar ratio is 1.

This mixture, kept stirring, was heated to 650 ml at ambient temperature.
Add cc of 6.9N ammonia solution at a rate of 100 c.c./hour, then add 1016 c.c. of 2.425N ammonia solution at the same flow rate.

The amount of base added in this way in the reaction medium accounts for 67 mol% of the theoretical amount required to completely neutralize the cerium and zirconium present in this reaction medium (OH ^- /Zr ⁴⁺ = 4 and
OH ^- /Ce ⁴⁺ = 4).

An aqueous colloidal dispersion was obtained exhibiting a CeO ₂ concentration of the order of 77.48 g/2 and a PH of approximately 2.

The hydrodynamic diameter of the colloid was determined to be approximately 350 Å by a test using pseudoelastic light diffusion on a sample (250 c.c.).

The determined Zr/Ce molar ratio was approximately 0.65.

Example 5 139.6 to 1744 c.c. of ceric nitrate solution containing 1.2 mol/cerium (), 0.05 mol/cerium () and having a free acidity of 0.5 N
g _{of zirconyl nitrate ZrO(NO3)2.2H2O are added} . The Zr ⁴⁺ /Ce ⁴⁺ molar ratio is 0.25.

This mixture, kept stirring, was heated to 1256 c.c. at ambient temperature.
6.19N ammonia solution at a rate of 100c.c./hour,
Then 696 c.c. of 2.4N ammonia solution is added at the same flow rate.

The amount of base added in this way in the reaction medium accounts for 82% of the theoretical amount required to completely neutralize the cerium and zirconium present in this reaction medium (OH ^- /Zr ⁴⁺ = 4, OH ^- /
Ce4 ⁺ = 4).

An aqueous colloidal dispersion was obtained with a CeO ₂ concentration of the order of 97 g/g and a pH of approximately 2.6.

Cerium quantification of the supernatant solution showed a very low total cerium concentration of the order of 3.5 g/ml, from which the amount of colloidal cerium in the supersaturated dispersion was determined to be approximately 96%.

The chemical composition of the material present in colloidal form in the aqueous sol was determined as described above.

The determined Cr/Ce molar ratio is about 0.13.

Claims (1)

[Claims] 1. An aqueous colloidal dispersion of a cerium () compound, wherein the cerium () compound has the following formula () Ce(OH) _4-x (NO ₃ ) _x () (where x is 0.3 ~0.7) and characterized in that the dispersion is supersaturated with OH ^- ions. 2. A colloidal dispersion according to claim 1, characterized in that it exhibits a very high amount of colloidal cerium that can reach 100%. 3. Colloidal dispersion according to claim 1 or 2, characterized in that it is capable of exhibiting high CeO ₂ concentrations which can be up to 30% by weight. 4. The colloidal dispersion according to any one of claims 1 to 3, which exhibits a large ionic force because it can contain 0.3 to 8 mol/base salt. 5. The colloid dispersion according to any one of claims 1 to 4, wherein the colloid exhibits a density of 3.5 to 6.0. 6. The colloid dispersion according to any one of claims 1 to 5, wherein the colloid has a hydrodynamic diameter of 50 to 400 mm. 7 OH ^- ion supersaturated product characterized by reacting an aqueous solution of cerium () salt with a base so as to obtain a supersaturation rate of 3 or more and 4 or less. A method for producing an aqueous colloidal dispersion of a cerium () compound of OH) _4-x (NO ₃ ) _x (), where x is 0.3 to 0.7. 8. The method according to claim 7, wherein the aqueous solution of cerium () salt is an aqueous ceric nitrate solution or an aqueous cerium ammonium nitrate solution. 9. The method according to claim 7 or 8, characterized in that the concentration of the cerium () salt is from 0.1 to 3 mol/mole/m expressed as cerium (). 10 The concentration of cerium () salt is cerium ()
10. The method according to claim 9, wherein the amount is 0.1 to 1.5 mol/. 11. The method according to any one of claims 7 to 10, wherein the basic solution is ammonia, an aqueous solution of caustic soda or potassium, or gaseous ammonia. 12. The method according to claim 11, wherein the basic solution has a normality of 5 to 11N. 13. The method according to claim 11, wherein the basic solution has a normality of 0.1 to 5N. 14. The method according to any one of claims 7 to 13, characterized in that the supersaturation rate is 3 or more and 3.8 or less. 15. The method according to claim 7, wherein the final pH of the colloidal dispersion of the cerium () compound is 3.0 or less. 16. The method according to claim 7, wherein the final pH of the colloidal dispersion of the cerium () compound is 0.3 to 3.0. 17. Process according to claim 7, characterized in that the temperature of the reaction between the aqueous solution of cerium () salt and the base is between 0°C and 60°C. 18. Process according to claim 17, characterized in that the selected reaction temperature is ambient temperature. 19. Claims 7 to 18 characterized in that an aqueous solution of cerium () salt and a basic solution are mixed simultaneously, or a base is added to an aqueous solution of cerium () salt, or vice versa. Any method described. 20. A method according to claim 19, characterized in that a concentrated basic solution is added followed by a dilute basic solution. Cerium () supersaturated with 21 OH ^- ions
Cation of compound and metal M (here metal M is 1b
Group, Group 2b, Group 3b, Group 4b, Group 5b, Group 6b, Group 7b, 8
selected from Groups 3a, 3a and 4a). 22. The hybrid aqueous colloid dispersion according to claim 21, wherein the cation of metal M is a metal cation having acidic properties. 23. The hybrid aqueous colloid dispersion according to claim 21 or 22, wherein the metal M is iron or zirconium. 24. The hybrid aqueous colloidal dispersion according to any one of claims 21 to 23, wherein 0.1 to 50% of the number of moles of cerium () is replaced by cations of metal M. 25 Claims 21 to 2, characterized in that the colloid has a hydrodynamic diameter of 50 to 2000〓
4. The hybrid aqueous colloid dispersion according to any one of Item 4. 26 Aqueous hybrid of cerium () compound and cation M ⁿ⁺ characterized by reacting an aqueous solution of cerium () salt and metal M salt with a base to obtain a supersaturation rate of 3 or more and 5.5 or less A method for producing a colloidal dispersion. 27. Claim No. 2, characterized in that the amount of base introduced accounts for 60 to 95 mol% of the theoretical amount of base necessary to completely suffice the cerium () and cations M ⁿ⁺ present in the reaction medium. The method according to item 26. 28 Solid metal M in a solution of cerium () salt
27. A method according to claim 26, characterized in that the salt of the compound is introduced and then the base is added. 29. Claim No. 2, characterized in that the salt of the metal M is made into an aqueous solution with a concentration from 0.01 mol/ to its maximum solubility, and this solution is mixed with an aqueous solution of the cerium () salt and then the base is added. The method according to item 26.